Feasibility Study on the Use of Modified Copper Slag as a Sustainable Fine Aggregate in Mortar

Abstract

Depending on the availability of aggregate sources pertaining to their geographic locations, the concrete industry utilizes conventional aggregates such as marine sand, dredged gravel, or crushed rocks. This method requires high energy and high processing costs for washing and grinding. The objective of this work is to use Modified Ferro silicate slag (MFS), a by-product obtained from the copper industry, as an alternative to the conventional fine aggregates found in mortar. No additional processing such as washing or grinding is required. By using the MFS slag as an aggregate in mortar or concrete, the factors of sustainability and a circular economy are enhanced. The current study focuses on the characterization of the MFS slag, including the mortar mixes with the MFS slag as a fine aggregate, and shows that the MFS slag can be a promising raw material to replace conventional aggregates in mortar. The leaching of its heavy elements such as Sb, As, Cr, Mo, Pb, and Zn was conducted well within limits (VLAREMA 4). The SEM and MIP analyses indicated that the porosity of the MFS slag mortar was higher compared to the standard aggregate mortar. Moreover, the MFS slag mortar showed acceptable resistance toward the alkali-silica reaction and carbonation.